Effect of motorcycle lighting configurations on drivers? perceptions of closing during nighttime driving

Objective: The aims were to better understand how drivers perceive an approaching set of motorcycle headlights during nighttime driving and to determine whether alternative motorcycle headlight configurations improve drivers' perceptual judgments of closing for an oncoming motorcycle.Background: Motorcyclists account for a disproportionate number of roadway fatalities, especially at night. One potential cause of this is drivers' misjudgments of a motorcycle's approach.Method: The first experiment examined whether drivers were more sensitive to horizontal or vertical optical expansion and whether drivers could integrate these two dimensions to achieve a lower looming threshold. A second experiment built on these results to test whether alternative headlight configurations that maximized size were better than other motorcycle headlight con-figurations and a car's headlights. In both experiments, participants were instructed to press a button to indicate when they first perceived an oncoming vehicle to be closing under nighttime driving conditions.Results: Headlight orientation did not affect when drivers perceived closing, and drivers were not able to integrate optical expansion from multiple dimensions in a way that achieves a lower looming threshold. However, the alternative motorcycle headlight configurations that accentu-ated the full extent of a motorcycle's size resulted in drivers perceiving closing sooner than other motorcycle headlight configurations but not sooner than a car.Conclusion: Drivers perceive closing sooner for larger headlight configurations except when the headlight configurations are relatively small, in which case the effect of headlight size is attenuated.Application: Drivers' perceptual judgments of motorcycles may improve when motorcycles have headlights that span its full height.